APPENDIX It is a colourless oil, b. p. 28o'J, with the properties of a weak secondary base, dissolving in acids, and forming easily hydro- lysable salts. The reaction described in this preparation is of a general character, and'furnishes a useful method for preparing members of thrs series of heterocyclic compounds. Diazobenzolimide condenses in a similar fashion with ketones (acetophenone) and dibasic esters (malonic. ester) as well as with ketonic esters, as in the present case. These substances possess the usual properties of cyclic compounds ; carboxyl may be removed as CO.,, and alkyl side-chains oxidised to carboxyl ; they may be stilphonated and nitrated, and the nitro-group reduced to an ami no-group ; the phenyl group attached to the nitrogen may also be removed by oxidation. Thus, phenylmethyltriazole carboxylic acid loses CCX on heating, and on oxidation the methyl group becomes carboxyl and can also be removed in the same way. The resulting product is phenyl triazole. The properties of the individual triazoles are influenced, like other cyclic compounds, by the groups attached to the nucleus, and to some extent also by the basic character of the mother substance. COHEN'S ADV. P. o. c.